Substrate processing method and substrate processing device

ABSTRACT

The present disclosure provides a substrate processing method and a substrate processing apparatus that perform selective film formation. The substrate processing method includes: forming a silicon-containing film by repeating forming an adsorption layer on a substrate on which a pattern of a concave portion is formed by supplying a silicon-containing gas to the substrate and generating plasma of a reaction gas to cause the plasma to react with the adsorption layer; and etching the silicon-containing film, wherein the forming the silicon-containing film includes modifying at least one of the adsorption layer and the silicon-containing film by generating a He-containing plasma.

TECHNICAL FIELD

The present disclosure relates to a substrate processing method and asubstrate processing apparatus.

BACKGROUND

For example, a substrate processing method of forming a film at adesired location is known.

Patent Document 1 discloses a protective film forming method ofperforming selective film formation on a flat surface between recessedshapes such as trenches by nitriding only the vicinity of the outermostsurface of a wafer to form an adsorption site while supplying afluorine-containing gas to a Si-containing base film to form anadsorption-inhibiting group, and then performing film formation.

PRIOR ART DOCUMENTS Patent Document

-   Patent Document 1: Japanese Laid-Open Patent Publication No.    2018-117038

In an aspect, the present disclosure provides a substrate processingmethod and a substrate processing apparatus that perform selective filmformation.

SUMMARY

In order to solve the above matters, according to an aspect, provided isa substrate processing method including: forming a silicon-containingfilm by repeating supplying a silicon-containing gas to a substrate onwhich a pattern of a concave portion is formed so as to form anadsorption layer on the substrate, and generating plasma of a reactiongas to cause the plasma to react with the adsorption layer; and etchingthe silicon-containing film, wherein the forming the silicon-containingfilm includes modifying the adsorption layer and/or thesilicon-containing film by generating plasma containing He.

According to an aspect, it is possible to provide a substrate processingmethod and a substrate processing apparatus that perform selective filmformation.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic view illustrating a configuration example of asubstrate processing system.

FIG. 2 is a schematic view illustrating a configuration example of afirst processing apparatus.

FIG. 3 is a flowchart illustrating an example of substrate processingperformed by the substrate processing system.

FIG. 4 is a time chart illustrating an example of an operation in thefirst processing apparatus.

FIG. 5 is a time chart illustrating an example of an operation in thefirst processing apparatus.

FIG. 6A is an example of a cross-sectional view of a wafer illustratinga SiN film after a SiN film forming step of the present example.

FIG. 6B is an example of a cross-sectional view of a wafer illustratinga SiN film after an etching step of the present example.

FIG. 6C is an example of a cross-sectional view of a wafer illustratinga SiN film after a SiN film forming step of a reference example.

FIG. 6D is an example of a cross-sectional view of a wafer illustratinga SiN film after an etching step of the reference example.

DETAILED DESCRIPTION

Hereinafter, embodiments of the present disclosure will be describedwith reference to the accompanying drawings. In each of the drawings,the same components will be denoted by the same reference numerals, andredundant descriptions thereof may be omitted.

[Substrate Processing System]

A substrate processing system according to the present embodiment willbe described with reference to FIG. 1 . FIG. 1 is a schematic viewillustrating a configuration example of the substrate processing system.

As illustrated in FIG. 1 , the substrate processing system includesprocessing apparatuses 101 to 104, a vacuum transfer chamber 200,load-lock chambers 301 to 303, an atmospheric transfer chamber 400, andload ports 501 to 503, and an overall controller 600.

The processing apparatuses 101 to 104 are connected to the vacuumtransfer chamber 200 via gate valves G11 to G14, respectively. Theinteriors of the processing apparatuses 101 to 104 are depressurized toa predetermined vacuum atmosphere so as to perform a desired processingon a wafer W. In an embodiment, the processing apparatus 101 is anapparatus that forms a SiN film on the wafer W. The processing apparatus102 is an apparatus that etches the SiN film formed in the processingapparatus 101. Each of the processing apparatuses 103 and 104 may be anapparatus that is the same as any of the processing apparatuses 101 and102, or may be an apparatus that performs other processing.

The interior of the vacuum transfer chamber 200 is depressurized to apredetermined vacuum atmosphere. The vacuum transfer chamber 200 isprovided with a transfer mechanism 201 capable of transferring the waferW in the depressurized state. The transfer mechanism 201 transfers thewafer W to the processing apparatuses 101 to 104 and the load-lockchambers 301 to 303. The transfer mechanism 201 includes, for example,two transfer arms 202 a and 202 b.

The load-lock chambers 301 to 303 are connected to the vacuum transferchamber 200 via gate valves G21 to G23, respectively, and connected tothe atmospheric transfer chamber 400 via gate valves G31 to G33,respectively. The interior of each of the load-lock chambers 301 to 303is configured to be capable of being switched between an air atmosphereand a vacuum atmosphere.

The interior of the atmospheric transfer chamber 400 is kept in an airatmosphere. For example, a down-flow of clean air is formed in theinterior of the atmospheric transfer chamber 400. Inside the atmospherictransfer chamber 400, an aligner 401 is provided to perform alignment ofthe wafers W. In addition, the atmospheric transfer chamber 400 isprovided with a transfer mechanism 402. The transfer mechanism 402transfers the wafer W to the load-lock chambers 301 to 303, carriers Cin the load ports 501 to 503 to be described later, and the aligner 401.

The load ports 501 to 503 are provided in the wall of a long side of theatmospheric transfer chamber 400. The carrier C in which the wafers Ware accommodated or an empty carrier C is mounted in each of the loadports 501 to 503. As the carrier C, for example, a front opening unifiedpod (FOUP) may be used.

The overall controller 600 controls respective parts of the substrateprocessing system. For example, the overall controller 600 executes theoperations of the processing apparatuses 101 to 104, the operations ofthe transfer mechanisms 201 and 402, the opening/closing of the gatevalves G11 to G14, G21 to G23, and G31 to G33, the switching of theinternal atmosphere of each of the load-lock chambers 301 to 303, andthe like. The overall controller 600 may be, for example, a computer

In addition, the configuration of the substrate processing system is notlimited to the above. The substrate processing system may be configuredto include a multi-wafer apparatus for processing a plurality of wafersW with a single apparatus, may be configured such that a vacuum transferchamber is also connected to the multi-wafer apparatus via a gate valve,or may be configured such that a plurality of vacuum transferapparatuses is connected to the substrate processing system.

Next, an exemplary configuration of the processing apparatus 101 will bedescribed. The processing apparatus 101 is an example of a firstprocessing apparatus that forms a SiN film by a plasma enhanced atomiclayer deposition (PE-ALD) method within a processing container kept in adepressurized state. FIG. 2 is a schematic view illustrating theconfiguration example of the processing apparatus 101.

As illustrated in FIG. 2 , the processing apparatus 101 includes aprocessing container 1, a stage 2, a shower head 3, an exhauster 4, agas supply mechanism 5, an RF power supply 8, and a controller 9.

The processing container 1 is made of a metal such as aluminum, and hasa substantially cylindrical shape. The processing container 1accommodates the wafer W. A carry-in/out port 11 for carrying in orcarrying out the wafer W therethrough is formed in the sidewall of theprocessing container 1. The carry-in/out port 11 is opened/closed by agate valve 12. An annular exhaust duct 13 having a rectangular crosssection is provided on a main body of the processing container 1. A slit13 a is formed along an inner peripheral surface of the exhaust duct 13.An exhaust port 13 b is formed in an outer wall of the exhaust duct 13.On a top surface of the exhaust duct 13, a ceiling wall 14 is providedto close an upper opening of the processing container 1 via an insulatormember 16. A space between the exhaust duct 13 and the insulator member16 is hermetically sealed with a seal ring 15. A partition member 17partitions the interior of the processing container 1 into upper andlower portions when the stage 2 (and a cover member 22) is raised to aprocessing position (to be described later).

The stage 2 horizontally supports the wafer W inside the processingcontainer 1. The stage 2 is formed in a disk shape having a sizecorresponding to the wafer W, and is supported by a support member 23.The stage 2 is formed of a ceramic material such as AlN or a metallicmaterial such as aluminum or a nickel alloy. A heater 21 for heating thewafer W is embedded in the stage 2. The heater 21 generates heat usingpower from a heater power supply (not illustrated). In addition, thewafer W is controlled to have a predetermined temperature by controllingthe output of the heater 21 by a temperature signal of a thermocouple(not illustrated) provided in the vicinity of the top surface of thestage 2. The cover member 22 formed of ceramic, such as alumina, isprovided on the stage 2 to cover an outer peripheral region of the topsurface and a side surface of the stage 2.

The support member 23 that supports the stage 2 is provided on thebottom surface of the stage 2. The support member 23 extends from thecenter of the bottom surface of the stage 2 downward of the processingcontainer 1 through a hole formed in the bottom wall of the processingcontainer 1. A lower end of the support member 23 is connected to alifting mechanism 24. By the lifting mechanism 24, the stage 2 is raisedand lowered between a processing position illustrated in FIG. 1 and atransfer position indicated by the alternate long and two short dashline below the processing position through the support member 23. At thetransfer position, the wafer W is capable of being transferred. A flange25 is provided on the support member 23 below the processing container1. A bellows 26, which is configured to isolate an internal atmosphereof the processing container 1 from ambient air and to be flexible withthe vertical movement of the stage 2, is provided between the bottomsurface of the processing container 1 and the flange 25.

Three wafer support pins 27 (of which only two are illustrated) areprovided in the vicinity of the bottom surface of the processingcontainer 1 to protrude upward from a lifting plate 27 a. The wafersupport pins 27 are moved upward and downward via the lifting plate 27 aby a lifting mechanism 28 provided below the processing container 1. Thewafer support pins 27 are inserted through respective through-holes 2 aprovided in the stage 2 located at the transfer position and areconfigured to move upward and downward with respect to the top surfaceof the stage 2. By raising/lowering the wafer support pins 27, the waferW is delivered between a wafer transfer mechanism (not illustrated) andthe stage 2.

The shower head 3 supplies a processing gas into the processingcontainer 1 in the form of a shower. The shower head 3 is made of ametal and provided to face the stage 2, and has a diameter, which issubstantially equal to that of the stage 2. The shower head 3 includes amain body 31 fixed to the ceiling wall 14 of the processing container 1and a shower plate 32 connected to the lower side of the main body 31. Agas diffusion space 33 is formed between the main body 31 and the showerplate 32 and is provided with a gas introduction hole 36 to penetratethe centers of the ceiling wall 14 of the processing container 1 and themain body 31. An annular protrusion 34 protruding downward is formed ona peripheral edge portion of the shower plate 32. Gas ejection holes 35are formed in a flat surface inside the annular protrusion 34. In thestate in which the stage 2 is located at the processing position, aprocessing space 38 is formed between the stage 2 and the shower plate32, and the top surface of the cover member 22 and the annularprotrusion 34 are close to each other to form an annular gap 39.

The exhauster 4 exhausts the interior of the processing container 1. Theexhauster 4 includes an exhaust pipe 41 connected to the exhaust port 13b, and an exhaust mechanism 42 connected to the exhaust pipe 41 andincluding a vacuum pump, a pressure control valve, and the like. Duringa process, the gas in the processing container 1 reaches the exhaustduct 13 via the slit 13 a, and is exhausted from the exhaust duct 13through the exhaust pipe 41 by the exhaust mechanism 42.

The gas supply mechanism 5 supplies a processing gas into the processingcontainer 1. The gas supply mechanism 5 includes a precursor gas source51 a, a reaction gas source 52 a, an Ar gas source 53 a, an Ar gassource 54 a, and a He gas source 55 a.

The precursor gas source 51 a supplies a precursor gas into theprocessing container 1 through a gas supply line 51 b. In the exampleillustrated in FIG. 2 , a dichlorosilane (DCS) gas is used as theprecursor gas. In the gas supply line 51 b, a flow rate controller 51 c,a storage tank 51 d, and a valve 51 e are interposed from an upstreamside. A downstream side of the valve 51 e of the gas supply line 51 b isconnected to the gas introduction hole 36 through the gas supply line56. The precursor gas supplied from the precursor gas source 51 a istemporarily stored in the storage tank 51 d before being supplied intothe processing container 1, is boosted to a predetermined pressureinside the storage tank 51 d, and is then supplied into the processingcontainer 1. The supply and cutoff of the precursor gas from the storagetank 51 d to the processing container 1 are performed by opening/closingthe valve 51 e. By temporarily storing the precursor gas inside thestorage tank 51 d as described above, it is possible to stably supplythe precursor gas into the processing container 1 at a relatively largeflow rate.

The reaction gas source 52 a supplies a reaction gas into the processingcontainer 1 through a gas supply line 52 b. In the example illustratedin FIG. 2 , a NH₃ gas is used as the reaction gas. In the gas supplyline 52 b, a flow rate controller 52 c and a valve 52 e are interposedfrom an upstream side. A downstream side of the valve 52 e of the gassupply line 52 b is connected to the gas introduction hole 36 throughthe gas supply line 56. The reaction gas supplied from the reaction gassource 52 a is supplied into the processing container 1. The supply andcutoff of the reaction gas to the processing container 1 are performedby opening/closing the valve 52 e.

The Ar gas source 53 a supplies an Ar gas as a purge gas into theprocessing container 1 through a gas supply line 53 b. In the gas supplyline 53 b, a flow rate controller 53 c and a valve 53 e are interposedfrom an upstream side. A downstream side of the valve 53 e of the gassupply line 53 b is connected to the gas supply line 51 b. The Ar gassupplied from the Ar gas source 53 a is supplied into the processingcontainer 1. The supply and cutoff of the Ar gas to the processingcontainer 1 are performed by opening/closing the valve 53 e.

The Ar gas source 54 a supplies an Ar gas as a purge gas into theprocessing container 1 through a gas supply line 54 b. In the gas supplyline 54 b, a flow rate controller 54 c and a valve 54 e are interposedfrom an upstream side. A downstream side of the valve 54 e of the gassupply line 54 b is connected to the gas supply line 52 b. The Ar gassupplied from the Ar gas source 54 a is supplied into the processingcontainer 1. The supply and cutoff of the Ar gas to the processingcontainer 1 are performed by opening/closing the valve 54 e.

The He gas source 55 a supplies a He gas as a modifying gas formodifying a film into the processing container 1 through a gas supplyline 55 b. In the gas supply line 55 b, a flow rate controller 55 c anda valve 55 e are interposed from an upstream side. A downstream side ofthe valve 55 e of the gas supply line 55 b is connected to the gassupply line 52 b. The He gas supplied from the He gas source 55 a issupplied into the processing container 1. The supply and cutoff of theHe gas to the processing container 1 are performed by opening/closingthe valve 55 e.

In addition, the processing apparatus 101 is a capacitively coupledplasma apparatus, in which the stage 2 serves as a lower electrode andthe shower head 3 serves as an upper electrode. The stage 2 serving asthe lower electrode is grounded via a capacitor (not illustrated).

Radio-frequency power (hereinafter, also referred to as “RF power”) isapplied to the shower head 3 serving as the upper electrode by the RFpower supply 8. The RF power supply 8 includes a feeding line 81, amatcher 82, and a radio-frequency power source 83. The radio-frequencypower source 83 is a power source that generates radio-frequency power.The radio-frequency power has a frequency suitable for plasmageneration. A frequency of the radio-frequency power is, for example, afrequency in the range of 450 KHz to 100 MHz. The radio-frequency powersource 83 is connected to the main body 31 of the shower head 3 via thematcher 82 and the feeding line 81. The matcher 82 includes a circuitfor matching an output reactance of the radio-frequency power source 83and a reactance of a load (the upper electrode). Although the RF powersupply 8 has been described as applying the radio-frequency power to theshower head 3 serving as the upper electrode, the present disclosure isnot limited thereto. The RF power supply 8 may be configured to applythe radio-frequency power to the stage 2 serving as the lower electrode.

The controller 9 is, for example, a computer, and includes a centralprocessing unit (CPU), a random access memory (RAM), a read only memory(ROM), an auxiliary storage device, and the like. The CPU operates basedon a program stored in the ROM or the auxiliary storage device andcontrols the operation of the processing apparatus 101. The controller 9may be provided either inside or outside the processing apparatus 101.In the case in which the controller 9 is provided outside the processingapparatus 101, the controller 9 is capable of controlling the processingapparatus 101 through a wired or wireless communication mechanism.

Next, returning to FIG. 1 , the processing apparatus 102 will bedescribed. The processing apparatus 102 is an example of a secondprocessing apparatus that performs etching process. The processingapparatus 102 is, for example, a dry etching apparatus, and etches theSiN film formed on the wafer W with plasma of an etching gas. Theprocessing apparatus 102 may be an atomic layer etching (ALE) apparatus,but is not limited thereto. The processing apparatus 102 may be providedas a separate apparatus without being connected to the substrateprocessing system, and may be, for example, a wet etching apparatususing dilute hydrofluoric acid (DHF), in which the SiN film formed onthe wafer W may be wet-etched.

Next, an example of substrate processing performed by the substrateprocessing system illustrated in FIG. 1 will be described. FIG. 3 is aflowchart illustrating an example of the substrate processing performedby the substrate processing system. In the wafer W in which an unevenpattern such as a trench is formed, the substrate processing systemselectively forms the SiN film on the pattern.

In step S101, the SiN film is formed on the wafer W in which an unevenpattern such as a trench is formed (SiN film forming step). This step isperformed in, for example, the processing apparatus 101.

An example of an operation of the processing apparatus 101 will bedescribed with reference to FIG. 4 by taking, as an example, the case offorming the SiN film by the PE-ALD process. FIG. 4 is a time chartillustrating an example of the operation in the first processingapparatus 101.

The PE-ALD process illustrated in FIG. 4 is a process of repeating aprecursor gas supply step S201, a purging step S202, a He gas supplystep S203, an RF power application step S204, a purging step S205, areaction gas supply step S206, an RF gas application step S207, and apurging step S208 in predetermined cycles to alternately supply aprecursor gas and a reaction gas and form a SiN film having a desiredfilm thickness on the wafer W. In FIG. 4 , only one cycle isillustrated.

The precursor gas supply step S201 is a step of supplying the precursorgas to the processing space 38. In the precursor gas supply step S201,first, in the state in which the valves 53 e and 54 e are opened, the Argas is supplied from the Ar gas sources 53 a and 54 a via the gas supplylines 53 b and 54 b. In addition, by opening the valve 51 e, theprecursor gas is supplied to the processing space 38 inside theprocessing container 1 from the precursor gas source 51 a via the gassupply line 51 b. In this case, the precursor gas is temporarily storedin the storage tank 51 d and then supplied into the processing container1. As a result, the precursor is adsorbed on the surface of the wafer Wso that an adsorption layer of the precursor is formed on the surface ofthe wafer W.

The purging step S202 is a step of purging the excess precursor gas orthe like in the processing space 38. In the purging step S202, the valve51 e is closed to stop the supply of the precursor gas while the supplyof the Ar gas via the gas supply lines 53 b and 54 b is continued. As aresult, the Ar gas is supplied to the processing space 38 inside theprocessing container 1 from the Ar gas sources 53 a and 54 a via the gassupply lines 53 b and 54 b. As a result, the excess precursor gas or thelike in the processing space 38 is purged. By closing the valve 51 e,the storage tank 51 d is filled with the precursor gas.

The He gas supply step S203 is a step of supplying the He gas to theprocessing space 38. In the He gas supply step S203, the valve 55 e isopened while the supply of the Ar gas via the gas supply lines 53 b and54 b is continued. As a result, the He gas is supplied to the processingspace 38 from the He gas source 55 a to the processing space 38 via thegas supply line 55 b.

The RF power application step S204 is a step of exciting the He gas toplasma. In the RF power application step S204, the plasma is generatedin the processing space 38 by applying RF to the upper electrode by theradio-frequency power source 83 while the supply of the Ar gas via thegas supply lines 53 b and 54 b and the supply of the He gas via the gassupply line 55 b are continued. As a result, the adsorption layer on thesurface of the wafer W is modified.

The purging step S205 is a step of purging the He gas or the like in theprocessing space 38. In the purging step S205, the valve 55 e is closedto stop the supply of the He gas while the supply of the Ar gas via thegas supply lines 53 b and 54 b is continued. In addition, theradio-frequency power source 83 stops applying RF to the upperelectrode. As a result, the Ar gas is supplied to the processing space38 inside the processing container 1 from the Ar gas sources 53 a and 54a via the gas supply lines 53 b and 54 b. As a result, the He gas andthe like in the processing space 38 are purged.

The reaction gas supply step S206 is a step of supplying the NH₃ gas asa reaction gas. In the reaction gas supply step S206, the valve 55 e isclosed to stop the supply of the He gas and the valve 52 e is openedwhile the supply of the Ar gas via the gas supply lines 53 b and 54 b iscontinued. As a result, the reaction gas is supplied to the processingspace 38 from the reaction gas source 52 a to the processing space 38via the gas supply line 52 b.

The RF power application step S207 is a step of exciting the NH₃ gassupplied as a reaction gas to plasma. In the RF power application stepS207, the plasma is generated in the processing space 38 by applying RFto the upper electrode by the radio-frequency power source 83 while thesupply of the Ar gas via the gas supply lines 53 b and 54 b and thesupply of the reaction gas via the gas supply line 52 b are continued.As a result, the adsorption layer on the surface of the wafer W isnitrided to generate the SiN film.

The purging step S208 is a step of purging the excess reaction gas orthe like in the processing space 38. In the purging step S208, the valve52 e is closed to stop the supply of the reaction gas while the supplyof the Ar gas via the gas supply lines 53 b and 54 b is continued. Inaddition, the radio-frequency power source 83 stops applying RF to theupper electrode. As a result, the Ar gas is supplied to the processingspace 38 inside the processing container 1 from the Ar gas sources 53 aand 54 a via the gas supply lines 53 b and 54 b. As a result, the excessreaction gas and the like in the processing space 38 are purged.

By repeating the above cycle, the SiN film is formed in conformity to anuneven pattern formed on the wafer W.

Here, a preferable range of conditions under which the SiN film isformed using the DCS gas and the NH₃ gas in step S101 are shown below.

Temperature: 250 to 600 degrees C.

Pressure: 0.5 to 10 Torr

Flow rate of DCS gas: 10 to 100 cc/cycle

Flow rate of NH₃ gas: 500 to 10,000 sccm

Flow rate of He gas: 100 to 10,000 sccm

Flow rate of Ar gas: 500 to 10,000 sccm

Time required for step (S201): 0.05 to 2.0 sec

Time required for step (S202): 0.1 to 2.0 sec

Time required for step (S203): 0.0 to 2.0 sec

Time required for step (S204): 1.0 to 6.0 sec

Time required for step (S205): 0.0 to 2.0 sec

Time required for step (S206): 0.5 to 2.0 sec

Time required for step (S207): 1.0 to 6.0 sec

Time required for step (S208): 0.1 to 2.0 sec

RF power during modification (S204): 10 to 1,000 W

RF power during nitration (S207): 50 to 1,000 W

Further, the precursor gas purging step S202 may be omitted, ormodifying steps S203 and S204 using the He plasma may be performed afterthe precursor gas supply step S201. In addition, the He gas may besupplied in a simultaneous manner in a step other than step S207.

The processing in step S101 is not limited to that illustrated in FIG. 4. Another example of the operation of the processing apparatus 101 willbe described with reference to FIG. 5 by taking, as an example, a caseof forming a SiN film by the PE-ALD process. FIG. 5 is a time chartillustrating another example of the operation of the first processingapparatus 101.

The PE-ALD process illustrated in FIG. 5 is a process of repeating aprecursor gas supply step S301, a purging step S302, a reaction gassupply step S303, an RF power application step S304, a purging stepS305, a He gas supply step S306, an RF gas application step S307, and aHe gas purging step S308 in predetermined cycles to alternately supply aprecursor gas and a reaction gas and form the SiN film having a desiredfilm thickness on the wafer W. In FIG. 5 , only one cycle isillustrated.

That is, in the process illustrated in FIG. 4 , after adsorption of theprecursor gas (S201) and before the nitriding processing of theprecursor gas (S206 and S207), modifying processing with the He gasplasma (S203 and S204) is performed.

In contrast, in the process illustrated in FIG. 5 , after adsorption(S301) and nitriding processing (S303 and S304) of the precursor gas,modifying processing with the He gas plasma (S306 and S307) isperformed. The processing of each step is the same as those of theprocess illustrated in FIG. 4 , and the description thereof will beomitted.

In the process illustrated in FIG. 5 , by repeating the above-describedcycle, the SiN film is formed in conformity to the uneven pattern formedon the wafer W, as in the case of the process shown in FIG. 4 .

Alternatively, after forming the SiN film having a desired filmthickness by repeating the adsorption and the nitriding processing ofthe precursor, a step of modifying the SiN film using He plasma may beperformed. In this case, the formation of the SiN film and the modifyingwith the He plasma may be performed in the same processing apparatus ormay be performed in different processing apparatuses.

Further, in the process illustrated in FIG. 4 , the step S205 of purgingthe excess He gas may be omitted. In the process illustrated in FIG. 5 ,the purging step S308 of purging the excess He gas may be omitted.Furthermore, the modifying with the He gas plasma may be performed bothafter the adsorption of the precursor gas and after the nitridingprocessing of the precursor gas.

Returning to FIG. 3 , in step S102, the SiN film formed on the wafer Wis etched (etching step). This step is processed in, for example, theprocessing apparatus 102. Here, as will be described later, the SiN filmin the concave portion is etched with priority over the SiN film on theupper portion of the pattern. This leaves the SiN film on the upperportion of the pattern. That is, the SiN film is selectively formed onthe upper portion of the pattern in step S101 and step S102.

In step S103, it is determined whether or not a repeat terminationcondition is satisfied. Specifically, steps S101 and S102 are repeateduntil a predetermined number of repetitions is satisfied (S103, “No”) sothat the SiN film formed on the upper portion of the pattern has adesired film thickness. When the predetermined number of repetitions issatisfied (S103, “Yes”), the process is terminated.

FIGS. 6A to 6D are examples of cross-sectional views of the wafer Winthe state in which the processing of the SiN film forming step S101 andthe etching step S102 were performed. Here, the SiN film forming stepS101 and the etching step S102 illustrated in FIG. 3 were performed onthe wafer W on which an uneven pattern 700 such as trenches is formed.FIG. 6A is an example of a cross-sectional view of the waferillustrating a SiN film 710 after the SiN film forming step S101 of thepresent example. FIG. 6B is an example of a cross-sectional view of thewafer illustrating a SiN film 720 after the etching step S102 of thepresent example.

In addition, in a reference example, the modifying gas was changed fromthe He gas to the H₂ gas, and the SiN film forming step S101 and theetching step S102 were similarly performed. FIG. 6C is an example of across-sectional view of the wafer illustrating a SiN film 730 after theSiN film forming step S101 of the reference example. FIG. 6D is anexample of a cross-sectional view of the wafer illustrating a SiN film740 after the etching step S102 of the reference example.

In the reference example, as illustrated in FIG. 6C, the SiN film 730 isformed in conformity to the uneven pattern 700 formed on the wafer W bythe SiN film forming step S101. Here, in the modifying processing usingthe H₂ plasma illustrated in the reference example, overall modifying isachieved by hydrogen ions, argon ions, and hydrogen radicals so thatetching resistance is improved.

As a result, as illustrated in FIG. 6D, the SiN film 740 after theetching process is maintained in the conformal state. That is, the SiNfilm remains not only in the upper portions of the pattern 700, but alsoin the concave portions.

In contrast, in the present example, as illustrated in FIG. 6A, the SiNfilm 710 is formed in conformity to the uneven pattern 700 formed on thewafer W in the SiN film forming step S101. Here, in the modifyingprocessing using the He plasma illustrated in the present example,vacuum ultra-violet (VUV) is emitted by plasmarization of He. In themodifying processing using the He plasma illustrated in the presentexample, the film is mainly modified by being irradiated with VUV.

On the other hand, the pattern 700 formed on the wafer W has beenminiaturized. Therefore, a width of an opening of each concave portionformed in the wafer W is shorter than a wavelength of the VUV. As aresult, the VUV incident from the opening becomes near-field light andstays in the vicinity of the entrance of the opening. Thus, the filmformed on the sidewalls in the vicinity of the entrance of the openingare modified by the incidence of the VUV which has become the near-fieldlight. Meanwhile, since the VUV does not propagate to the film formed oninner sidewalls or bottoms of the concave portion, the film is notmodified by the VUV. The film formed on the upper surface of the concaveportion is modified by the incidence of the VUV. That is, in the SiNfilm 710, the film formed on the upper portion of the pattern 700 (theupper surface of the convex portion and the sidewalls in the vicinity ofthe entrance of the opening) is selectively modified and improved in theetching resistance. In other words, an etching rate of the SiN filmformed on the upper portion of the pattern is lower than that of the SiNfilm formed on the inner sidewalls or the bottom of the concave portion.

As a result, as illustrated in FIG. 6B, in the SiN film 720 after theetching process, the SiN film formed on the inner sidewalls and thebottoms of the concave portions is preferentially etched, and the SiNfilm formed on the upper portions of the pattern 700 remains. That is,the SiN film can be selectively formed on the upper portions of thepattern 700 in steps S101 and S102.

Here, the range of the SiN film 720 after the etching processillustrated in FIG. 6B corresponds to the range of the modified SiNfilm, and further corresponds to the range in which the VUV isirradiated. It is known that an exudation length of the near-field lightis about the magnitude of the width of the opening. As illustrated inFIG. 6B, it can be confirmed that the SiN film on the sidewalls in thevicinity of the entrance of the opening after the etching processremains by an amount corresponding to substantially the magnitude of thewidth of the opening, in other words, the film is modified in the rangein which the VUV which has become the near field light stays.

In the foregoing, the film forming method of the present embodimentusing the processing apparatuses 101 and 102 has been described.However, the present disclosure is not limited to the above-describedembodiment or the like, and various modifications and improvements arepossible within the scope of the gist of the present disclosuredescribed in the claims.

The processing apparatuses 101 and 102 has been described to betransferred through the vacuum transfer chamber 200, but the presentdisclosure is not limited thereto. The processing apparatuses 101 and102 may be transferred in an atmospheric transfer manner.

In addition, the processing apparatus 101, which performs the formationof the SiN film and the modification using the He plasma, and theprocessing apparatus 102, which performs the etching process, have beendescribed as being provided separately, but not limited thereto. Theformation of the SiN film and the modification using the He plasma, andthe etching process may be performed in a single processing apparatus.

In the processing apparatus 101, the precursor gas has been described tobe DCS and the reaction gas has been described to be the NH₃ gas, butthe present disclosure is not limited thereto. As the precursor gas, asilicon-containing gas, such as a halogen-containing silicon-based gas,an aminosilane gas, a SiH₄ gas, or a trisilylamine (TSA) gas, may beused. As the reaction gas, a gas such as a NH₃ gas or a N₂ gas may beused. When the SiH₄ gas is used as the precursor gas, the N₂ gas may beused as the reaction gas. In addition, in the second film forming stepS103, the SiN film may be formed by a thermal ALD instead of using theplasma. In this case, a gas such as NH₃, hydrazine, or a hydrazinederivative may be used as the reaction gas.

The present application claims priority based on Japanese PatentApplication No. 2019-210529 filed on Nov. 21, 2019, the disclosure ofwhich is incorporated herein in its entirety by reference.

EXPLANATION OF REFERENCE NUMERALS

101 to 104: processing apparatus, 200: vacuum transfer chamber, W:wafer, 1: processing container, 2: stage, 3: shower head, 4: exhauster,5: gas supply mechanism (gas source), 51 a: precursor gas source, 52 a:reaction gas source, 53 a: Ar gas source, 54 a: Ar gas source, 55 a: Hegas source, 8: RF power supply (radio-frequency power supply), 83:radio-frequency power source, 9: controller

1.-13. (canceled)
 14. A substrate processing method comprising: forminga silicon-containing film by repeating forming an adsorption layer on asubstrate on which a pattern of a concave portion is formed by supplyinga silicon-containing gas to the substrate and generating plasma of areaction gas to cause the plasma to react with the adsorption layer; andetching the silicon-containing film, wherein the forming thesilicon-containing film includes modifying at least one of theadsorption layer and the silicon-containing film by generating aHe-containing plasma.
 15. The substrate processing method of claim 14,wherein, in the modifying the at least one of the adsorption layer andthe silicon-containing film, the at least one of the adsorption layerand the silicon-containing film is modified by being irradiated withlight of the He-containing plasma.
 16. The substrate processing methodof claim 15, wherein an opening width of the concave portion is shorterthan a wavelength of the light of the He-containing plasma.
 17. Thesubstrate processing method of claim 16, wherein, in the modifying theat least one of the adsorption layer and the silicon-containing film,the at least one of the adsorption layer and the silicon-containing filmformed on an upper portion of the pattern formed on the substrate ismodified.
 18. The substrate processing method of claim 17, wherein, themodifying the at least one of the adsorption layer and thesilicon-containing film improves an etching resistance of thesilicon-containing film.
 19. The substrate processing method of claim18, wherein the modifying the at least one of the adsorption layer andthe silicon-containing film is performed after repeating the forming theadsorption layer and the generating the plasma of the reaction gas. 20.The substrate processing method of claim 19, wherein the forming thesilicon-containing film and the etching the silicon-containing film arerepeated.
 21. The substrate processing method of claim 20, wherein thesilicon-containing film is a SiN film.
 22. The substrate processingmethod of claim 21, wherein the silicon-containing gas includes at leastone selected from a group consisting of a halogen-containingsilicon-based gas, an aminosilane gas, a SiH₄ gas, and a trisilylamine(TSA) gas.
 23. The substrate processing method of claim 22, wherein thereaction gas includes at least one selected from a group consisting of aNH₃ gas, a N₂ gas, a hydrazine, and a hydrazine derivative gas.
 24. Thesubstrate processing method of claim 14, wherein an opening width of theconcave portion is shorter than a wavelength of the light of theHe-containing plasma.
 25. The substrate processing method of claim 14,wherein, in the modifying the at least one of the adsorption layer andthe silicon-containing film, the at least one of the adsorption layerand the silicon-containing film formed on an upper portion of thepattern formed on the substrate is modified.
 26. The substrateprocessing method of claim 14, wherein, the modifying the at least oneof the adsorption layer and the silicon-containing film improves anetching resistance of the silicon-containing film.
 27. The substrateprocessing method of claim 14, wherein the modifying the at least one ofthe adsorption layer and the silicon-containing film is performed afterthe forming the adsorption layer.
 28. The substrate processing method ofclaim 14, wherein the modifying the at least one of the adsorption layerand the silicon-containing film is performed after the generating theplasma of the reaction gas.
 29. The substrate processing method of claim14, wherein the modifying the at least one of the adsorption layer andthe silicon-containing film is performed after repeating the forming theadsorption layer and the generating the plasma of the reaction gas. 30.The substrate processing method of claim 14, wherein the forming thesilicon-containing film and the etching the silicon-containing film arerepeated.
 31. The substrate processing method of claim 14, wherein thesilicon-containing film is a SiN film.
 32. The substrate processingmethod of claim 14, wherein the silicon-containing gas includes at leastone selected from a group consisting of a halogen-containingsilicon-based gas, an aminosilane gas, a SiH₄ gas, and a trisilylamine(TSA) gas.
 33. A substrate processing apparatus comprising: a processingcontainer including a stage on which a substrate is placed; a gas sourceconfigured to supply a gas into the processing container; aradio-frequency power supply configured to apply radio-frequency powerto the processing container to generate plasma inside the processingcontainer; and a controller, wherein the controller includes: forming asilicon-containing film by repeating forming an adsorption layer on asubstrate on which a pattern of a concave portion is formed by supplyinga silicon-containing gas to the substrate and generating plasma of areaction gas to cause the plasma to react with the adsorption layer; andetching the silicon-containing film, wherein the forming thesilicon-containing film includes modifying at least one of theadsorption layer and the silicon-containing film by generating aHe-containing plasma.